Maastrichtian Climatic History of the Southern Oceans

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Results of preliminary strontium, oxygen and carbon isotope studies have revealed progressive cooling, and significant climatic and oceanographic variability during the Maastrichtian. Episodes of marked increases in foraminiferal del 18O values correlate with decreases in oceanic del 13C values, documented sea level regressions, and increases in seawater 87Sr/86Sr ratios in the early to late and latest Maastrichtian. The coincidence of these events, and the similarity between Maastrichtian benthic foraminifera del 18O values and those of middle Eocene age associated with ice-rafted debris, suggest that the Maastrichtian isotopic variations could be related to glacio-eustatic phenomena. The research proposed will investigate and document the climatic and oceanographic history of the high and mid-latitude South Atlantic and Indian Oceans from the latest early Maastrichtian to the Cretaceous-Tertiary boundary based on foraminiferal oxygen and carbon isotope measurements, and foraminiferal quantitative analyses. We will attempt to determine the effect of climatic/oceanographic changes on foraminiferal populations. Stratigraphic correlation of deep-sea sections will be enhanced by integration of biostratigraphy, magnetostratigraphy and chemostratigraphy. This data set is expected to provide a basis for climatic reconstruction of the Late Cretaceous including development of new climatic models that are not based on the assumption of uniform, warm, and equable climatic conditions during the Cretaceous.